Chlorine-containing vinyl resins stabilized with a tri-(2-alkenyl)-phosphite and a 1,2-epoxy compound



. light.

Patented Dec. 14, 1948 CHLORINE-CONTAINING VINYL RESINS STABILIZED WITHA TRI-(Z-ALKENYLF PHOSPHITE AND A LZ-EPOXY COM- POUND Henry J. Richter,Glen Ellyn, Ill., assignor to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware No Drawing. ApplicationFebruary 4, 1948, Serial No. 6,342

11 Claims. 1

This invention relates to chlorine-containing vinyl resin compositionsand to methods for preventing or retarding their discoloration by heator light. More specifically this invention relates tochlorine-containing vinyl polymers and copolymers showing improvedresistance to discoloration on exposure to the action of heat or lightand to methods for their preparation.

In many applications of' chlorine-containing vinyl polymers, as forexample vinyl chloride polymers and copolymers, it is necessary tosubject the vinyl resin to elevated temperatures to permit formationinto various products. These vinyl resins tend to decompose somewhat onheating which decomposition is generally recognized by the developmentof color. Even though slight decomposition on heating may not detract toany appreciable extent from the physical properties of the resin, thediscoloration seriously restricts its use in many applications. The useof these resins is further restricted due to discoloration andembrittlement which takes place on exposure to light. Heretofore, a widevariety of materials have been disclosed to function as stabilizers forchlorine-containing vinyl resins by minimizing discoloration on exposureto heat or However, such stabilizers have not been entirelysatisfactory, particularly in preventing discoloration of vinyl chlorideresins under strong exposure to light and at elevated temperatures.

This application is a continuation of my application Serial No. 694,167,filed August 30, 1946, now abandoned.

It is an object of this invention to provide chlorine-containing vinylresin compositions showing improved resistance to discoloration onexposure to the action of heat and light. A further object of thisinvention is to provide a method for preventing or substantiallyretarding the discoloration of vinyl chloride resin compositions onexposure to heat and light. A still further object is to providepolymers and copolymers of vinyl chloride stabilized againstdecomposition by heat or light. Other objects will appear hereinafter.

These objects are accomplished by the preparation of compositions ofmatter comprising a chlorine-containing vinyl resin of 14-75% by weightchlorine and having the chlorine attached directly to the carbon atomsin the polymer chain; from 1 to 6% by weight, based on the resin, of atri-(Z-alkenyD-phosphite having 3-14 carbons in each alkenyl group; andfrom 0.1 to 5.0% by weight, based 'on the resin, of a 1,2-

epoxy compound having a boiling point above 200 C. at atmosphericpressure. In some instances it is advantageous to add from 0.1 to 3.0%by weight, based on the resin, of an alkali or alkaline earth metal saltof a fatty acid of from 10 to 18 carbon atoms.

Examples of tri(2-alkenyl)phosphites include tri- (2-propenyl)phosphite(triallyl phosphite), tri (2-methyl-2-propenyl) phosphite (trimethallylphosphite), and trl-(2-butenyDphosphite (tricrotonyl phosphite). Thetri-(2-alkenyl)phosphites containing 3 to 4 carbon atoms in each alkenylgroup and having a terminal CH2=C group in each alkenyl group arepreferred for use in this invention. The proportion of unsaturatedphosphite may be varied widely, but

from 1 to 6%, based on the weight of dry resin, is preferred.

This invention is generic to the use of 1,2- epoxy compounds. For mostpurposes the higher boiling 1,2-epoxides are preferred, namely thoseboiling above 200 C. and up to 400 C. at atmospheric pressure, sincecompositions containing these compounds retain their resistance todiscoloration due to heat and light under more drastic conditions andfor longer periods of time. Although in general, 0.1 to 5% of epoxycompound based on the weight of the dry resin, is sufiicient to obtainthe desired effect in the stabilizer combination of this invention, bestresults are obtained howeverwith 1.0 to 5%.

The salts of fatty acids suitable for use in the practice of thisinvention are the alkali metal and alkaline earth metal salts of fattyacids containing 10 to 18 carbon atoms, including sodium decanoate andmagnesium laurate. Magnesium stearate and sodium stearate are among thereadily available fatty acid salts which are preferred for use in thisinvention. In general, 0.1 to 3% of fatty acid salts, based on theweight of the dry resin, is sufficient to produce the desired effect.

The stabilized chlorine-containing vinyl resin compositions of thisinvention are prepared by adding to the chlorine-containing vinylpolymer the tri(2-alkenyl)phosphite and at least one member of the classconsisting of the abovedescribed 1,2-epoxy compounds and alkali oralkaline earth metal salts of long chain fatty acids containing 10 to 18carbon atoms. Any convenient method may be employed to incorpo; rate thestabilizers with the chlorine-containing vinyl polymers. However, bestresults are obtained by mixing the polymers, for example, thoseresulting from the polymerization of vinyl chloride, or from theconjoint polymerization of vinyl chloride and another polymerizablemonomer, with the stabilizer, for example 3% of a tri(2 aikenyDphosphiteand 2% of a 1,2-epoxy compound, with or without the aid of a volatilesolvent, and milling the resulting mixture on rolls at 100 to 160 C.until completely It is not desirable to continue milling any longer thanrequired to homogenize the mixture since long milling will cause somediscoloration of the resin. It is therefore advantageous to mix theresin and stabilizers thoroughly before milling. The stabilized resin isremoved from the mill in the form of a sheet of the desired thicknessand may be used as such or subjected to a polishing treatment. It isparticularly desirable to remove the sheeting from the mill at atemperature of about 145 to 160 C. since at lower temperatures thesheeting obtained is somewhat brittle.

Polished films are readily prepared by heating the milled sheet, underpressure, between highly polished plates. Although the optimumtemperature for polishing varies with the type of resin being used, ingeneral it is preferred to employ a temperature of about 150 to 160 C.and a pressure of about 250 to 500 lbs/sq. in.

Stabilized sheeting, obtained by milling the resin and stabilizers, mayalso be chopped mm the desired size for injection molding purposes. Thismilling procedure is readily adaptable to the preparation of stabilizedvinyl chloride resin compositions containing plasticizer, pigment, dyeand the like, which may then be used for lacquers, spinning of fibers,film casting, and fabric coatings.

Another method of incorporating the stabilizers of this invention is tomake a thick slurry of the'resin with some liquid which is a nonsolventfor the polymer and an inert solvent for the stabilizer combination.Suitable solvents include diethyl ether, aliphatic hydrocarbons,preferably those having low boiling points, and the lower aliphaticalcohols where excessive heat can be avoided. The solvent is allowed toevaporate leaving the stabilizer composition uniformly distributed overthe polymer. This drying operation is conveniently carried out in arotary drier.

In certain instances, it may be desirable to prepare the stabilizedchlorine-containing vinyl resin compositions of this invention by addingthe stabilizer combination to the polymer dispersion as it is obtainedfrom the polymerization vessel in accordance with the process describedin the patent application of H. W. Arnold, Serial No. 427,921, nowPatent No. 2,404,780 filed January 23, 1941. If this procedure isfollowed, it is desirable to bring the pH of the dispersion to about '7to avoid decomposition of the 1,2-epoxy compound. In this process careshould be used in selecting the unsaturated phosphite since the lowermembers of the series are somewhat hydrolyzed by water. The dispersionis filtered to remove any large lumps of resin and then coagulated byfreezing or by the addition of an electrolyte, such as sodium chlorideor aluminum sulfate solution. The precipitated polymer is washed withwaterto remove residual surface homogenized.

4 therewith, can be stabilized against the discoloration action of heatand light by means of the process of this invention.

The selection of the particular stabilizer combination to be useddepends to a large extent on the final use to which thesechlorine-containing vinyl resins are to be put. A combination ofunsaturated phosphite and 1,2-epoxy compound or a combination ofunsaturated phosphite and a salt of a fatty acid is particularlyeffective in resistance to discoloration on outdoor exposure and tofadeometer exposure. For outstanding resistance to discoloration onexposure to sunlight, it is preferred to use as the stabilizercombination, a mixture of unsaturated phosphite and phenoxypropyleneoxide, or a mixture of unsaturated phosphite and magnesium stearate. Thestabilizer comprising the combination of 3 parts of triallyl phosphiteand 0.5 to 1 part of magnesium stearate has shown exceptional resistanceto discoloration on outdoor exposure. In many cases with thesecompositions if a slight initial color forms during fabrication, it isbleached out on exposure to sunlight.

If compositions showing exceptional heat stability are desired, it ispreferred to use as the stabilizing agent a combination of unsaturatedphosphite, a 1,2-epoxy compound of relatively low volatility at ordinarytemperatures, that is having a boiling point at atmospheric pressure ofover 200 C., for example, betanaphthoxypropylene oxide, and from 0.1 to3% of an alkaline earth salt of a long chain fatty acid, for example,magnesium stearate. This composition is outstanding with respect tostability at elevated temperatures. I

The invention is further illustrated by the following examples in whichparts are given by weight, unless otherwise specified.

EXAMPLE I A mixture comprising parts of the copolymer obtained bypolymerizing a mixture of vinyl chloride and diethyl fumarate in theratio of 1 part of the latter to 19 of the former, 3 parts of triallylphosphite, 2 parts of beta-naphthoxypropylene oxide, and 0.5 part ofmagnesium stearate is thoroughly homogenized by working on a roll millheated to C. for 5 minutes. The composition thus produced is removed inthe form of a colorless film. Sheeting prepared by heating this film atC. under pressure between polished chromium plated steel plates for 2minutes is clear and colorless and shows only a slight discolorationafter heating for 2 hours at 125 C. This film is outstanding inresistance to discoloration on exposure in the fadeometer as indicatedby the fact that it remains colorless after 96 hours exposure.

A film prepared under similar conditions but without the addedstabilizer combination discolors to a grey-green on heating for 2 hoursat 125 C. and to black after only 48 hours exposure in thefadeometer.Films containing 1% of magnesium stearate as the only stabilizerdiscolor badly on heating and also turn black after 48 hours fadeometerexposure. A film of the same resin containing 2% beta-naphthoxypropyleneoxide as the only added stabilizer shows some resistance todiscoloration on heating but discolors to a very deep red after 96 hoursfadeometer exposure. A film of the same resin containing 3 parts oftriallyl phosphite as the only stabilizer speckles in 48 hoursfadeometer expou e and turns black after 96 hours.

ene oxide A mixture comprising 100 parts of the copolymer obtained bypolymerizing a mixture of vinyl ExAmrLn III A mixture comprising 100parts of polyvinyl chloride, 3 parts of triallyl phosphite, 2 parts ofbeta-naphthoxypropylene oxide, and 0.5 part of magnesium stearate ,ishomogenized by working on a roll mill heated to 150 to 154 C. for tenminutes. The product obtained is subdivided, dissolved in 60:40 methylethyl ketone:toluene and flowed on to a glass plate. After evaporationof the solvent there is obtained an essentially colorless film .003 inchthick. This film remained perfectly colorless after 124 hours exatedpolyethylene with no stabilizer present, was subjected to the sametreatment as a control. Each composition was removed from the rolls inthe form of a slab and a sample of this slab was molded into a disc at150-160 C. and 2000 lbs./ sq. in. for 10 minutes. As shown in the table,composition (B) containing magnesium stearate alone as the additive andcomposition (D) contalning no added agent were dark brown, indicatingdecomposition, whereas compositions (A) and (C), and in particularcomposition (C). showed marked superiority in heat stability under theseconditions.

v Samples of compositions (A), (B), (C), and (D) were cut from each ofthe rolled slabs and subjected to a further heat stability test at 180C.-in an atmosphere of air for 2 hours. The air was swept over thesamples in place of the more conventional nitrogen in order to providemore extreme conditions for testing the stability of the resin. At theend of 2 hours the amount of acid (mostly hydrogen chloride) liberatedfrom the samples was measured by titration with standard alkali andexpressed as milligrams of hydrogen chloride evolved per gram of resin.The results posure in a fadeometer. are included in the table.

Table Parts Sta- I Mg. HCl Added Stabilizer 13? Liberated fm I Resin perg. Resin A beta-Naphthoxypropyl- 2 3.3 Yellow.

ene oxide. 3 aglr1iesiu1r1nste1aate.. 0.; 3.7 Dk. Brown.

Ila Y 03 l B..--

beta 8p thoxyprm 2 2. 7 Very pale yellow.

pylene oxide. Magnesium steal-ate... 0. 5 D No Stabilizer 7.0 Dk. brown.

Exlunu: IV

Additional compositions prepared by milling a mixture of powdered vinylchloride/diethyl fumarate (/5) copolymer with selected combinations ofstabilizer are set forth in the following table. Films made from thesecompositions were polished by hot pressing between chromium plates andsubjected to the indicated tests. In the first column, therev is giventhe stabilizers in parts by weight to parts of the copolymer resin. Thefour additional columns give respectively the color of the polished film(a) after polishing, (b) after 2 hours at C., (c) after 96 hoursfadeometer exposure, and (d) after outdoor exposure of the stated numberof months.

In addition to the copolymers of vinyl chloride with diethyl fumarate,copolymers of vinyl chloride with dimethyl, di-n-butyl, di-isobutyl,dicyclohexyl, dibenzyl, and di-(chloroethyDfumarate or maleate, andcopolymers of vinyl chloride with the di-esters of fumaric or maleicacid with methoxy, ethoxy-, or butoxyethanol may be used for thepreparation of the compositions of this invention. Copolymers containingfrom 80 to 97% vinyl chloride with from 20 to 3% of an ethylenedicarboxylic acid ester, particularly a di-ester of fumaric acid or adi-ester of maleic acid are preferred copolymers for use in thisinvention. There may also be employed copolymers of vinyl chloride withvinyl esters of organic acids, such Stabilizer Parts/100 0i Resin ColorPolished Film 22 gf Color 96 hours Fadeometer gggggg No stabilirer Grey.l Grey-green Black in 48 hours Deep tred in 2 mon 3 Triallyl Phosphlte',1 Sodium Stearate- Very slight color Quite Tan Fewredspecksin iiihours.Quite Colorless after 4 Light greenish brown- 3 Triollyl Phosphite, 2Phenoxypropyl- 2 Beta-naphthoxy-propylene oxide, 0.5

Sodium Stearate.

spotty red in 96 hrs. months.

:QEXAMPLE V .Onehundred'parts of chlorinated polyethylene 7 containing27% .chlorine by weight was thoroughly 'mi-xed-on rolls heated at C. for3 minutes=with various quantities of stabilizers as noted for (A), (B),and (C) in the table below.

as vinyl acetate and vinyl propionate, containing 80 to 97 vinylchloride, copolymers of vinyl chloride and vinylidene chloride, andcopolymers of vinyl chloride with acrylates, such as methyl acrylate,ethyl acrylate and butyl acrylate, and also copolymers of vinyl chloridewith methacry- Composition (D), which consisted of the chlorini5 lates,such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate,containing from 80 to 97% of vinyl chloride. In general, copolymers ofvinyl chloride with one other ethylenically unsaturated compound, whichcontain 80-97% vinyl chloride can be stabilized in accordance with thisinvention.

The polymers and copolymers of vinyl chloride may be prepared by any ofthe processes well known in the art. Suitable methods includepolymerization in aqueous emulsions, in solution, in ketonic solvents,in hydrocarbon nonsolvents for the resins, such as n-hexane, and also inthe absence of solvents and nonsolvents.

A wide variety of catalysts may be used to accelerate thepolymerization, Such catalysts as sodium, potassium or ammoniumpersulfate are preferred for preparing the resin by an aqueous emulsionprocess. Acyl peroxides, such as benzoyl peroxide, lauroyl peroxide,acetyl peroxide, and also hydrogen peroxide may be used. In thepreparation of the resins by the polymerization of the monomer ormonomers in aqueous emulsion, it is desirable to use surface-activeagents, a procedure which is well known in the art.

Chlorinated polyethylenes having chlorine contents varying from about14% to about 75% chlorine by weight may also be used for the preparationof the compositions of this invention. The chlorinated polyethylenes maybe prepared by chlorinating polyethylenes of various molecular weightsin solution or in aqueous suspension as described in U. S. P. 2,183,556to Fawcett and in the patent application of Robert S. Taylor, Ser. No.686,149, filed July 25, 1946.

The unsaturated phosphites are readily prepared from phosphorustrichloride and the desired unsaturated alcohol by carrying out thereaction in the presence of a hydrogen chloride acceptor, such aspyridine or dimethyl aniline, with ether or benzene as the reactionmedium. A suitable process is described by Milobendzki and Sachnowski(Chem. Abs-13, 2865 (1919)). Un-

V saurated alcohols that may be used for the preparation of theunsaturated phosphites having 3 Caution should be exercised in thepreparation of these compounds since some of them tend to decomposevigorously at elevated temperatures. Those unsaturated phosphitesderived from high boiling alcohols are preferably purified by a Washingprocedure.

Some of the 1,2-epoxy compounds suitable for the practice of thisinvention are common and easily obtainable, such as ethylene oxide andepichlorohydrin. Other types, such as the glycide ethers, are preparedby well known procedures given in the literature (Lindmann, Ber. 24,2416 (1891), Boyd and Marle, J. Chem. Soc. 93, 840 (1909) Examples of1,2-epoxy compounds are phenoxypropylene oxide, phenoxybutylene oxide,alpha naphthoxypropylene oxide, beta naphthoxypropylene oxide,parachlorophenoxypropylene oxide, cresoxypropylene oxide, diglycideethers, esters of epoxypropionic acid, and alkyl or aryl substitutedethylene oxides, such as ethylethylene oxide and benzylethylene oxide.

Combinations of chlorine-containing vinyl resins with atri(2-alkenyl)phosphite and an alkali or alkaline earth metal salt of afatty acid containing -18 carbon atoms; with a tri(2-alkenyDphosphiteand a 1,2-epoxy compound; and

8 with a tri(2-alkenyl) phosphite, 1,2-epoxy compound, and an alkali oralkaline earth metal salt of a fatty acid containing 10-18 carbon atoms,can be prepared by any method of mixing desired. For

- example, a vinyl chloride polymer can be dissolved in a suitablesolvent, such as cyclohexanone, methyl ethyl ketone-xylene, methylisobutyl ketone-xylene, acetone-toluene, acetone, and tetrohydrofurane,and the stabilizer comb:ination added to this solution.

Such solutions either with or without the addition of plasticizer,pigment, dyes and fillers can be used for the production of variousarticles, spinning of fibers, film casting or fabric coating. Thesestabilizers can also be incorporated into the resin alone, or inconjunction with fillers, plasticizers, pigments and the like, with theaid of a solvent in a Banbury mixer and the resultant product can beused for coating fabrics by a calendering procedure. The stabilizedproducts of this invention may also be dissolved in a volatile solventand used as a lacquer.

The compositions of this invention can be used for the preparation ofmolding powders, coatings for metals and fabrics, films and foils. Ifdesired, the chlorine-containing vinyl resin composition stabilizedaccording to the process of this invention may be combined with orprepared in the presence of plasticizers, dye softeners or othersynthetic resins.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

I claim:

1. A composition of matter comprising a chlorine-containing vinyl resinof 14 to by weight chlorine'in which the chlorine is attached directlyto the carbon atoms in the polymer chain, from 1 to 6% by weight, basedon said resin, of a tri-2-alkenyl)phosphite having 3 to 14 carbons ineach alkenyl group, and from 0.1 to 5.0% by weight based on said 'resin,of a 1,2-epoxy compound having a boiling point above 200 C.

2. A composition of matter comprising a chlorine-containing vinyl resinof 14 to 75 by weight chlorine in which the chlorine it attacheddirectly to the carbon atoms in the polymer chain, from 1 to 6% byweight, based on said resin, of

. a tri-(2-alkenyl) phosphite in which each alkenyl group contains 3 to4 carbon atoms and has a terminal CH2=C' group, and from 0.1 to 5.0% byweight, based on said resin, of a 1,2-epoxy compound having a boilingpoint above 200 C.

3. A composition of matter comprising a chlorine-containing vinyl resinof 14 to 75 by weight chlorine in which the chlorine is attacheddirectly to the carbon atoms in the polymer chain, from 1 to 6% byweight, based on said resin, of triallyl phosphite, and from 0.1 to 5.0%by weight, based on said resin, of a 1,2-epoxy compound having a boilingpoint above 200 C.

4. A composition of matter comprising a chlorine-containing vinyl resinof 14 to 75 by weight chlorine in which the chlorine is attacheddirectly to the carbon atoms in the polymer chain, from 1 to 6% byweight, based on said resin, of triallyl phosphite, and from 0.1 to 5.0by weight, based on said resin, of phenoxy-propylene oxide.

5. A composition of matter comprising a chlorine-containing vinyl resinof 14 to 75% by weight chlorine in which the chlorine is attacheddirectly to the carbon atoms in the polymer chain.

sisting of alkali and alkaline earth metal salts of fatty acidscontaining from 10 to 18 carbon atoms. I

6. A composition of matter as set forth in claim 5 in which saidtri-(2-alkenyDphosphite is triallyl phosphite.

l. A composition of matter comprising a chlorine-containing vinyl resinof 14 to 75% by weight chlorine in which the chlorine is attacheddirectly to the carbon atoms in the polymer chain, from 1 to 6% byweight, of triallyl phosphite, from 0.1 to 5.0% by weight, based on saidresin, 01 beta-naphthoxypropylene oxide and from 0.1 to 3.0% by weight,based on said resin, of magnesium stearate.

8. A composition of matter comprising a chlorine-containing vinyl resin,from 1 to 6% by weight, based on said resin, of a tri-(2 -alkenyl)-phosphite having 3 to 14 carbons in each alkenyl group, and from 0.1 to5.0% by weight, based on said resin, of a 1,2-epoxy compound having aboiling point above 200 C., v

taining vinyl resin consisting of a copolymer of.

said chlorine-con- 80 to 97% vinyl chloride and 20 to 3% of an ethylenedicarboxylic acid ester. I

9.,A composition of matter as set forth in claim 8 in which saidtri-(2-alkenyl)phosphite is triallyl phosphite.

10. A composition of matter comprising a chlorine-containing vinylresin, from .1 to 6% by weight, based on said resin, of 'atri-(Z-alkenyl) phosphite having 3 tom carbons in each alkenyl group,from 0.1 to 5.0% by weight, based on said resin, of a 1,2-epox compoundhaving a boiling point above 200 0., and from 0.1 to 3.0% by weight,based on said resin, of a fatty acid salt selected from the classconsisting of alkali and alkaline earth metal salts of fatty acidscontaining from 10 to 18 carbon atoms, said chlorinecontaining vinylresin consisting of a copolymer of 80 to 97% vinyl chloride and 20 to 3%of an ethylene dicarboxylic acid ester,

11 A composition of matter as set forth in claim 10 in which saidtri-(2-alkenyDphosphite 1s triallyl phosphite.

I HENRYJ.RICH'IER.

v No references cited.

